The SAP Analytics Cloud mobile app allows users to view and interact with stories, collaborate with colleagues using comments and notifications, and share links to stories via email or other apps. Users cannot create stories, datasets, or models using the mobile app. Verified Reference: [SAP Analytics Cloud - Mobile App]

When a model includes a prompt, the prompt is presented at runtime before data can be displayed in the story. The prompt allows users to select the values they want to filter the data by. The prompt is not related to the predefined widgets, the rendering of widgets, or the navigation to widgets. Verified Reference: [SAP Analytics Cloud - Prompting]

You can define a calculation for a table in three ways:
Table: You can add a simple calculation by selecting two measures in a table, right-clicking, choosing Add calculation, and choosing the calculation you want. You can also add a repeating or single column or row to a table by right-clicking on a measure or dimension and choosing Add Calculation1.
Calculation editor: You can open the calculation editor from the drop-down menu of Measures or Dimensions in the Designer Panel and create complex calculations for a chart or table. For each type of calculation, a new calculated member is created. You can also use dimension attributes as part of a calculation2.
Story: You can create a calculated measure in the Builder pane of a story. When setting up your calculation, you apply the typical formula functions, conditions, and operators to the data contained in your model. Calculated measures allow you to perform mathematical and Boolean operations on your data1.
Reference:
1: Calculating Data in Stories - SAP Learning 2: SAP Analytics Cloud In-story Calculation Series - An Introduction